It's so extremely buggy! I upgraded to Golden Gate early (tho after release) because everyone (including here) said it's so much better than Tahoe, but it has fixed no bugs which annoyed me with Tahoe and introduced so many new ones. Mission Control frequently switches to the wrong window (perfectly reproducible bugs which result in the wrong window coming forward). And in Mission Control, windows now overlap each other, are overlapped by the dock, and end up partially outside the screen, in ways they just never did in any earlier macOS release. The Launchpad replacement part of Spotlight in 26 was always super buggy but has gotten even more buggy in 27. Just yesterday the WiFi menu in the menu bar beach balled.

iOS text input is also super buggy now, with frequent rendering glitches where the new blue words from "AI" suggestions or whatever overlap other text, there are stale blue squiggles which are hold-overs from grammatical issues which have since been fixed, completely nonsensical grammatically nonsense suggestions, etc.

The decrease in quality from 15 to 26 and then 26 to 27 is staggering.